Presentation of experimental results on stability of a 3 DOF 4-cable-driven parallel robot without constraints

This paper presents the findings of several experiments done on the stability of a planar thfee degree-of-freedom (DOF) cable-driven parallel manipulator. The major interest is the deflection caused by a wrench or force applied normal to the plane. Here the planar cable robot has no direct constraint. A simple mathematical model based on stiffness is presented to predict the outcomes. It was found that a planar cable robot of dimensions four by l 0 m deflects between 20 and 400mm under forces up to 50N applied through the normal. Deflections under movement were found to be small in comparison. Oscillations frequencies are in the range of 0.5- 1 Hz. The results are also compared to a big mock up robot with dimensions eight by twenty meters. The deHections on this mock-up were found to be very similar to those found on the robot after considering scale